Device for maintaining uniform contact and pressure between alpha stationary and revolving body for electrical machines



May 11 1 926. 1,584,059

w 0. WHEELER DEVICE FOR MAINTAINING uNIi'oRN CONTAG'LQIAND PRESSURE BETWEEN A STATIONARY ANDREVOUI'IIIG BODY FOR"; ELECTRICAL MACHINES Filed June 2'1, I924 45 I 19 21 a Hil 6 I N l f- 26' I k 10- I W 17 fizz 622%)".

(ZZZ/Izaak); K5 4 Patented May 11, 1926 e it so STATES:

WILLIAM C. WHEELER, OF CHICAGO, ILLINOIS.

DEVICEIFOB MAINTAINING UNIFORM CONTACT AND PREBSURE BETWEEN A STA- T-IONARY AND REVOLVING BODY FOR ELECTRICAL MACHINES;

Application filedJune 27, 1924;

This invention relates toa device for maintaining uniform contact and pressure between a stationary and revolving body for electrical machines.

One of the objects of the present inventionis to provide airimproved means whereby a predetermined and uniform pressure may be maintained between the contacting points ofa stationary and a revolving body in an electrical machine;

A further object of the invention is to provide a generally improved contact making body such ascarbonbruslies which prolongs the life of'the'same and thereby econ omizes in the number of replacements;

A further object of" the invention is-to provide an improved carbon brush holding device for electrical motors or generators and the like whereby the adjustment of the carbon with respect to the armature may be readily made as wear insues on the-carbon brush.

A still further object of the invention is to-provide means for'indicating the spring pressure and adjusting the spring pressure on the carbon brush.

A still further object of the invention is to provide a substantially enclosed casing for the carbon brush and thereby prevent accumulation of dirt and" foreign particles on the sides of the brush which ordinarily interfere with the proper operationof the view of my improved carbon brush holder showing the relative position of the different parts with respect to the casing.

Fig. 3 is an end elevational view of the casing of my improved carbon brush holder, and

Serial No.- 722,674.

Fig.4 is a cross sectional view taken on the lines 4. l in: Fig; 2 and looking in the direction indicated by the arrows.

One of the essential features of my invention is the provision of an improved means for maintaining proper contact so. as

to accomplish: proper current connection 0 between the revolving armature and sta tionarybrush holder of electrical machines. Theinventionin the present iustance is particularly directed to carbon brushes as the medium of transmitting the current from the revolving armature tothe stationaryv member, but it will, of course, be understood that other contacting mediums may be used and. still be within the contemplation of my invention. culty has been experienced in connection with maintaining proper and uniform tension ofthe carbon brush which contacts with the revolving armature and considerable difliculty has also been experienced in connection with the accumulation of dirt and foreign materials on the sides of the carbon brush interfering with the uniform flow of: current from one body to the other.

To overcome these difficulties I have provided' a brush holder in the form of a sub stantially enclosed casing 10 which is preferably provided with a longitudinally rectangular opening 11 which extends through the casing; The casing is preferably provided with a plurality of weight reduction apertures 13 and a transversely extending rib 14, whiclris adapted to engage any convenient groove, as shown at 15, formed in the frame member 16 of the conventional form of generator shown in Fig. 1. The casing is provided with apertures 17 arranged on the oppositesides thereof for. the reception of' bolts 18 for securing the brush holder or casing to the frame of the motor or generator. Secured to the casing 10 by means of screws 19, which are in threaded engagement with the casing 10, as shown at 20, is a cap 21. The cap 21 is preferably provided with a recess as shownat 22, which is arranged around its perimeter for snugly seating the inner portion of the cap 21 into the upper end of the longitudinally eXtending aperture 11 of the casing 10. Slidably mounted in the longitudinally extending aperture 11 of the casing 10 is a contact Considerable diiii- 79 making body or carbon brush 23, which is of substantially the same dimensions or slightly smaller than the size or the rectangular opening 11 in the casing. Positioned in contact with the inner end or the carbon brush 23 and positioned in the rectangular opening 11 or the casing 10 is a plate 24. The plate 24: is provided with, on its outer ends, cylindrical lugs 25, which are adapted to engage and support oppositely disposed compression springs 26. Formed integrally with the plate 24, at the center thereof, is a cylindrical boss 27 which is adapted to engage and support and retain in position a third compressions spring 28. Secured to the boss 27 or the plate 2% in any preferred manner is a rod 29, which has a portion or its outer end threaded as shown at 30. Secured to the plate 2a between the springs 26 and 28 by means or rivets 31 are current shunts 32, which are preferably made of phosphor bronze. These shunts 32 have their ends bent upwardly and inclined outwardly, as shown at 33, with their extreme outer ends curved inwardly as shown at 34 to rrictionally engage the inner walls or the casing 10. This construction permits these shunts to engage the sides of the wall under tension and to insure positive contact with the inner sides of the wall of the casing. Positioned in the rectangular opening 11 or the casing 10 adjacent the cap 21 is a spring pressure plate 35, which is adjustably mounted therein, and is provided with on its outer ends two cylindrical lugs 36, which correspond to the lugs 25 on the plate 2a and are in alignment therewith for retainin and supporting the compression springs 26 in position. The plate 35 is further provided with a central cylindrical lug or boss 37, which corresponds to the boss 27 and co-operates therewith for supporting and maintaining the spring 28 in its operative position. EX- tending through the boss 37 and plate 35 is a central bore 38, which slidably receives the rod 29.

When wear insues on the carbon brush 23 it becomes necessary to adjust the plate 24 and plate 35 with their associated springs, and in order to make this adjustment 1 have provided a threaded bolt 39 which is provided with the usual head 49. The bolt 39 is positioned centrally or the cap 21 and is in threaded engagement vith a bore 4-1 in said cap. The lower end or the bolt is in contact with the outer surface or the plate 35, as shown at 42, and when it is necessary to adjust the carbon brush 23 by reason of wear on the brush in the longitudinal rectangular aperture 11 or the casing 19, the bolt 39 may be adjusted for accomplishing this purpose. In order to lock the bolt 39 in predetermined positions of adjustment I have provided a lock nut a3, which is in threaded engagement with the bolt and is provided on one side thereof with a conical portion 44;, which is adapted to engage an annular bevelled flange ii-5 formed integrally with the cap 21. acent the threaded aperture 41.

One of the essential features of my im proved brush holding mechanism is the provision of means :l'or maintaining a substantially uniform tension on the carbon brush up to the time the brush is completely worn down. This means comprises the providing or a longitudinal bore 46 in the bolt 39 which is adapted to reciprocally receive the rod The rod 29 is provided with a nut l? which is in threaded engagement with the threaded portion 30 or the rod and adapted to engage the upper side or the head 49 or the bolt 39 for effecting an adjustment and indicating the tension that is being exerted by the springs on the carbon brush 23. in order to lock the nut 47 in predetermined positions oi adjustment I have provided a lock nut 4L8.

in the operation or my improved brush holding mechanism it will, or course, be understood that a delinite spring tension must be exerted on the brush in accordance with the area or the brush in contact with the armature and that when this is determined the bolt 39 and the rod 29 are adjusted in such a manner as to exert the proper tension on the brush holder to insure the proper contacting pressure between a carbon brush and the armature. And when the brush holder and carbon brush are in their operative positions or in the position shown in Fig. 1 with the carbon contacting the armature the nut 47 will be slightly spaced, for example an eighth of an inch, "from the outer end or the head lO or the bolt 39 indicating that the springs 26 and 28 are under a predetermined pressure. This pressure, or course, is transmitted through the plate 24: to the carbon brush 23 and as wear insues on the brush the amount or wear on the carbon will be indicated by the reduction in the space between the nut a7 and the head a0 01 the bolt 39. When this space is reduced from its predetermined setting or an eighth of an inch it indicates that in order to bring the carbon brush 23 under its previously set spring tension, and retain the spring under tension uniformly, it is necessary to loosen the lock nut 4.3 and adjust the bolt 39 inwardly or the casing to a point in which the space between the nut t? and the head d0 of the bolt is the same as it was when it was originally set.

or course, it vill be understood that I have provided ample means whereby a wide range of varying spring tensions may be had, but in order to obtain the best results and elimina e unnecessary replacement or carbon brushes, previously determined spring pressure that is best suitable for the type or carbon employed should be mamtained throughout the life of the brush in order that the best results obtainable may be had.

From the above description it will be readily seen that I have provided a very simple and etiicient means whereby the spring tension on the carbon brush is indicatcd and additional means whereby the device may be adjusted to maintain uniform tension during the life of the carbon brush. it will also be noted that by positioning the carbon brush within substantially an enclosed casing that the possibility of dirt or other foreign material accumulating on. the sides of the brush and interfering with the etiicient operation of the brush is eliminated.

As previously pointed out the spring pressure exerted on the carbon brush is indicated by the relative position of the nut 47 secured to the rod 29 with respect to the top 01 the head of the bolt 40. In other words, when the spring tension on the carbon brush has been reduced by the wear thereon causing the plate to move in a direction toward the armature and carrying the rod 29 with its nut 47 inwardly toward the casing and thereby reducing the space between the nut t? and head 40 of the bolt/39, thereby indicating that the pressure oi the springs has been reduced from what it has been previously set at.

It will be further noted that I have provided a construction by means of which the length of unused brush still available for service after the brush has been in use for some time may be indicated by the relative position of the head 40 ot the bolt 39 with respect to the top of the lock nut 43 together with the space between the head 40 ot the bolt 39 and the nut a? of the rod 29. By reason of this construction the greatest service or life of the carbon brush is utilized consistent with the etficient operation of the brush and thereby cconomizing in the number of replacements and indicates the time when such replacements should be made.

It will be further understood from the above description that I have provided an improved form of carbon brush holder which substantially encases the whole carbon brush as well as the springs which resiliently press the carbon brush in contact with the armature and that by positioning the springs so that they exert a force on the carbon brush in a direction parallel with the movement of the carbon brush as it is worn down by the armature the difiiculty which has been encountered by the old style of spring exerted brush in which the torsional spring is positioned on one side of the brush and exerting a diagonal force on the brush instead of a longitudinal pressure has been overcome.

lVhile in the above specification I: have described one embodiment which my invention may assume in practice, it will, of course, be understood that the same is capable of modification and that modification may be made without departing from the spirit and scope of my invention as expressed in the following claims.

hat I claim as my invention and desire to secure by Letters Patent is:

1. In combination with an electrical machine of an armature therefor, a carbon brush holder comprising a casing adapted to be secured to said machine, said casing haveing an opening therein, a carbon brush mounted in said opening and adapted to have one end in contacting relation with said armature, a plate mounted in saidopening and engageable with the other end of said carbon brush, a second plate positioned in said opening adjacent said first named plate, and a plurality oi springs mounted between said plates for exerting pressure on said carbon brush.

2. In combination with an electrical machine of an armature therefor, a carbon brush holder comprising a casing adaptedto be secured to saidinachine, said casinghaving an opening therein, a carbon brush mounted in said opening and adapted to have one end in contacting relation with said armature, a plate mounted in said opening and engageable with the other end of said carbon brush, a second plate positioned in said opening adjacent said first named plate, aplurality of springs mounted between said plates for exerting pressure on said carbon brush, and means connected to said first named plate for indicating the spring pressure being exerted on said carbon brush.

3. In combination with an electrical machine of an armature therefor, a carbon brush holder comprising a casing adapted to be secured to said machine, said casing having an opening therein, a carbon brush mounted in said opening and adapted to have one end in contacting relation with said armature, a plate mounted in said opening and engageable with the other end of said carbon brush, a second plate positioned in said opening adjacent said first named plate, a plurality of springs mounted between said plates ior exerting pressure on said carbon brush, means connected to said first named plate for indicating the spring pressure being exerted on said carbon brush, and means whereby said springs and second named plate may be adjusted to maintain uniform pressure on the carbon brush.

4. In combination with an electrical machine ot an armature therefor, a carbon brush holder comprising a casing adapted to be secured in said machine, said casing having an opening therein, a carbon brush mounted in said opening and adapted to have one end in contacting relation with said armature, a plate mounted in said opening and engageable with the other end of said carbon brush, a second plate positioned in said opening adjacent said first named plate, a plurality of springs mounted between said plates for exerting pressure on said carbon brush, means connected to said first named plate for indicating the spring pressure being exerted on said carbon brush, and a bolt in threaded engagement with said casing and engageable with said second named plate whereby said spring and second named plate may be adjusted maintain uniform pressure on the carbon brush.

5. In combination with an electrical ma chine, of an armature therefor, carbon brush holder comprising a casing adapted to be secured in said machine, said casing having an opening therein, a carbon brush mounted in said opening and adapted to have one end thereof in contacting relation with said armature, plate mounted in said opening and engageable with the other end of said carbon brush, a second plate mounted in said opening, springs mounted between said plates for exerting resilient pressure on said carbon brush, a bolt adjustably con nected with said casing for regulating the tension of said springs, and means extending through said bolt and connected to said first named plate indicating the pressure exerted on said springs.

6. In combination with an electrical ma chine, of an armature therefor, a carbon brush holder comprising a casing adapted to be secured in said machine, said casing having an opening therein, a carbon brush mounted in said opening and adapted to have one end thereof in contacting relation with said armature, a plate mounted in said opening and engageable with the other end of said carbon brush, a second plate mount ed in said opening, springs mounted between said plates for exerting a resilient pressure on said carbon brush, a bolt adjustably connected with said casing for regulating the tension of said springs, and a rod extending through said bolt and connected to said first named plate indicating the pressure exerted on said springs.

In testimony whereof I have signed my name to this specification, on this 23rd day of June A. D. 1924.

WILLIAM C. WVHEELER. 

